I can't see color in Material tab
1.

It might be that your panels are arranged in a non-default way.

If you use Blender Render or Blender Internal renderer (which is the default in a newly installed Blender):


Find the Diffuse panel and change the color there


If you use Cycles renderer:


Find the Surface panel and change the color there






2.

It also might be that you have created the material in Blender Render and then switched to Cycles renderer, or vice versa - which makes the material color slot disappear since the Blender Render and Cycles materials are not compatible (unless you know your way in complicated node setups).

In this case, easy way is to just remove the incompatible material from the minus button and add a new material by clicking 'New'.



I hope this helps :)

If not, post a screenshot of your material panels to the first post, that would be helpful.